15-year-old Cori Gauff (right) was a surprise winner in the first round of Wimbledon. Photo: Toby Melville/Reuters

LONDON – Wimbledon hailed a new queen on Monday when 15-year-old Cori Gauff stunned five-time champion Venus Williams as opening day at the All England Club witnessed shock defeats for title hopefuls Naomi Osaka, Alexander Zverev and Stefanos Tsitsipas.

Gauff, already in the record books as the youngest player ever to qualify for the tournament, showed nerves of steel after squandering three match points in a tense conclusion on Court One.

She made just eight unforced errors while 39-year-old Venus committed 25 as the veteran American suffered only her second first round loss at Wimbledon – the first was in 1997.

Williams had already won two of her five Wimbledon titles by the time Gauff was born in 2004, but the teenager was unfazed.

"It's the first time I have ever cried after winning a match," said Gauff who took up the sport after being inspired by Venus and Serena Williams.

"At the net, Venus told me congratulations and keep going, she said good luck and I told her thanks for everything she did."

"I wouldn't be here if it wasn't for her -- I told her she was so inspiring. I've always wanted to tell her that but I've never had the guts."

On a day of seismic shocks, Japanese superstar Osaka slumped to a 7-6 (7/4), 6-2 defeat to 39th-ranked Yulia Putintseva of Kazakhstan who had defeated the world number two on grass in Birmingham two weeks ago.

US Open and Australian Open winner Osaka is the first top-two seed to lose in the first round since Martina Hingis in 2001.

"Can we stop now? I think I am going to cry," she told reporters as she made a quick exit from her post-match news conference.

Osaka has yet to make a final since her Australian Open win in January.

"There are answers to questions that you guys ask that I still haven't figured out yet," she admitted.

German sixth seed Zverev, 22, lost 4-6, 6-3, 6-2, 7-5 to Czech qualifier Jiri Vesely, the world number 124.

"Everything outside the court affects you, I won't get into details now, but the last couple of days have been very rough for me," said Zverev who has never got beyond the last 16.

Just 15 minutes after Zverev's defeat, 20-year-old Tsitsipas lost 6-4, 3-6, 6-4, 6-7 (8/10), 6-3 to world number 89 Thomas Fabbiano of Italy.

Tsitsipas had reached the semi-finals of the Australian Open in January and the last-16 at Roland Garros as well as the fourth round at Wimbledon last year.

"If I won today I would not have deserved it. It should have been over in three sets," said Tsitsipas.